The present invention relates generally to time management, and more particularly, to a method and apparatus of managing time for a processing system located on a machine.
Time management on a machine, such as an earth moving machine, is an important task. Time management on multi-processor systems is needed both for coordinated event logging, and also to ensure the controllers perform coordinated tasks at the appropriate time. Some systems, such as that disclosed in U.S. Pat. No. 6,012,004, attempt to have all of the controllers operate in lock step with each other. For example, the system may utilize one clock, located on a controller, such as a master controller. The master controller may determine the time and distribute the time to the other controllers. Without a local clock, the other controllers have no concept of time except what is delivered to them from the master controller. Therefore, keeping time with a desired resolution places a burden on the communication network. In addition, failures such as to the communication network or master controller, either temporary or long term, disrupts time management for the system because time updates are not performed. Therefore, time management is ineffective when failures occur.
The present invention is directed to overcome one or more of the problems set forth above.
In one aspect of the present invention, a method of managing time for a processing system located on a machine is disclosed. The processing system includes a plurality of controllers, each controller having a local clock. The processing system also includes a communication network connecting each of the controllers. The method includes the steps of, establishing an operating characteristic of the machine, and updating the local time of a controller in response to the operating characteristic.
In another aspect of the present invention, an apparatus configured to manage time on a processing system located on a machine is disclosed. The apparatus comprises a plurality of controllers, a local clock located on each controller and configured to update a local time, a communication network connected to the controllers, wherein each of the plurality of controllers are configured to establish an operating characteristic of the machine, and update the local time in response to the operating characteristic.